b. Cause: owing to, thanks to, on account of, in consequence of (cp. propter, ob): διὰ τοὺς θεοὺς ἐσῳζόμηνI was saved thanks to the godsD. 18.249, τι_μώμενος μὴ δι᾽ ἑαυτόν, ὰλλὰ διὰ δόξαν προγόνωνhonoured, not for himself, but on account of the renown of his ancestorsP.Menex. 247b. So in εἰ μὴ διά τινα (τι) had it not been for in statements of an (unsurmounted) obstacle: φαίνονται κρατήσαντες ἂν τῶν βασιλέως πρα_γμάτων, εἰ μὴ διὰ Κῦρονit seems they would have got the better of the power of the king, had it not been for CyrusI. 5.92.

c.διά is rarely used (in place of ἕνεκα) to denote a purpose or object: διὰ τὴν σφετέρα_ν δόξανfor the sake of their honourT. 2.89, δι᾽ ἐπήρειανfor spiteD. 39.32 (cp. διὰ νόσον ἕνεκα ὑγιεία_ςon account of disease in order to gain healthP.Lys. 218e).

d.διά with gen. is used of direct, διά with accus. of indirect, agency (fault, merit, of a person, thing, or situation). διά with gen. is used of an agent employed to bring about an intended result; διά with accus. is used of a person, thing, or state beyond our control (accidental agency). (1) Persons: ἔπρα_ξαν ταῦτα δι᾽ Εὐρυμάχουthey effected this by the mediation of EurymachusT. 2.2, τὰ διὰ τούτους ἀπολωλόταwhat has been lost by (the fault of) these menD. 6.34. The accus. marks a person as an agent not as an instrument. (2) Things: νόμοι, δι᾽ ὧν ἐλευθέριος ὁ βίος παρασκευασθήσεταιlaws, by means of which a life of freedom will be providedX.C. 3.3.52, διὰ τοὺς νόμους βελτί_ους γιγνόμενοι ἄνθρωποιmen become better thanks to the laws 8. 1. 22. Sometimes there is little difference between the two cases: δι᾽ ὧν ἅπαντ᾽ ἀπώλετοD. 18.33, δι᾽ οὓς ἅπαντ᾽ ἀπώλετο 18. 35.

e. For διά with accus. to express the reason for an action, the dative is sometimes used (1517): τοῖς πεπρα_γμένοις φοβούμενος τοὺς Ἀθηναίουςfearing the Athenians by reason of what had happenedT. 3.98. The dative specifies the reason less definitely than διά with the accusative.

f. When used in the same sentence, the dative may express the immediate, διά with the accus. the remoter, cause: ἀσθενείᾳ σωμάτων διὰ τὴν σι_τοδεία_ν ὑπεχώρουνthey gave ground from the fact that they were weak through lack of foodT. 4.36.

g.διά with accus. contrasted with ὑπό with gen.: φήσομεν αὐτὸ δι᾽ ἐκεῖνα ὑπὸ τῆς αὑτοῦ κακία_ς ἀπολωλέναιwe shall say that it (the body) is destroyed on account of those (remoter) causes (as badness of food) by its own evil (immediately) P.R. 609e.

δια- often denotes intensity, continuance, or fulfilment (διαμένεινremain to the end, διαφθείρεινdestroy completely). δια- is common in the reciprocal middle (1726), as in διαλέγεσθαιconverse; often of rivalry (οἱ διαπολι_τευόμενοιrival statesmen, διακοντίζεσθαιcontend in throwing the javelin).